The present invention relates to a shock device, and in particular a shock absorber for an at least partially muscle-powered two-wheeled vehicle, and in particular a bicycle and comprises at least one damping system having a damper cylinder and a moving piston disposed therein which is connected with a piston rod leading out of the damper cylinder. Particularly preferably, the invention relates to a suspension fork for an at least partially muscle-powered two-wheeled vehicle, and in particular a bicycle.
The prior art has disclosed a great variety of shock absorbers for bicycles with and without an electric auxiliary motor. The weight of at least partially muscle-powered bicycles plays a significant role, in particular where sports or competition bicycles are concerned. Weight reduction in bicycle components tends to involve significant work input.
Most mountainbikes come equipped with a suspension fork and a rear wheel shock absorber. The shock devices at the front and rear wheels serve to dampen shocks in downhill rides so as to increase comfort. Furthermore, the safety in riding can be increased since the bicycle wheels show improved traction.
Known suspension forks tend to be provided with a plurality of flow valves which control compression stage damping in dependence on the compressing speed. Other than control valves for low speeds, control valves for high speeds are also provided for supplying adapted and suitable damping characteristics over the entire speed range. The known rear wheel shock absorbers and suspension forks allow achievement of a wide scope of satisfactory properties.
It has been found, however, that in certain riding situations it may be difficult to obtain optimal damping characteristics in the compression stage. The center of gravity of a sitting rider during fast downhill rides is typically rather in the rearward area of the bicycle. The front wheel is thus unloaded and the suspension fork is firstly only slightly compressed. In these riding situations, it is per se desirable for the suspension fork to operate at weak compression stage damping, thus readily neutralizing small or medium-sized obstacles which the rider hardly feels in his hands and arms. This requires setting a weak compression stage damping. Now if a strong shock occurs, the available suspension travel may possibly not be very long so that a particularly hard high speed compression stage damping needs to be used. This may show the drawback that such strong damping will also be used for small shocks. Therefore, the suspension fork is less than optimally comfortable in rides involving minor obstacles.
WO 2014/190387 A1 has disclosed a shock absorber for bicycles in which a piston in a damper chamber separates two chambers filled with the damping fluid. The volume of the damping fluid displaced as the piston rod plunges in is guided to an external equalizing chamber where a dividing piston separates the working fluid from a gas chamber. In order to provide different damping strengths over the suspension travel, the damper chamber is surrounded by a cylindrical hollow space, and over the length of the damper chamber a plurality of bypass bores is provided which connect the damper chamber with the cylindrical hollow space. Thus, during compressing the damping force keeps increasing with increasing utilization of the suspension travel since the quantity of bypass connections decreases. In this way a stronger end position damping is realized as well. Although this known shock absorber is functional, it comprises a heavy steel spring and a complex structure requiring around the damper chamber a cylindrical hollow space having a plurality of bypass bores.
It is therefore the object of the present invention to provide a shock device showing a simpler structure and lighter weight for an at least partially muscle-powered two-wheeled vehicle, and in particular, a bicycle which in the case of minor shocks for example in fast downhill rides shows softer response, and which in the case of major obstacles or when hitting the ground following jumps and the like provides sufficiently long suspension travel.